Resonant Sensor Compliant Mounting for High-Temp Fluid Analysis
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Solution Overview
Problem
Resonant sensors for measuring downhole fluid properties face challenges in minimizing mounting effects on accuracy and repeatability, particularly due to thermal hysteresis and energy leakage, which are costly and require high precision manufacturing.
Innovation Solution
A fluid properties measurement device with a resonator supported at its central vibrational node by flexible supports, driven and sensed in torsional motion, using a compliant mounting structure to minimize mounting effects and separate resonant modes, and employing electromagnetic transducers with soft magnetic materials to reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resonator is mounted to a physical support structure, then the resonator can be held in position and operated, but mounting effects cause energy leakage and damping that reduce measurement accuracy and repeatability
Solution Approach 1:
A compliant mounting structure acts as an intermediary between the resonator and the rigid support frame. This compliant structure isolates the resonator from direct mechanical coupling to the frame, thereby reducing energy leakage and damping effects while still providing positional support. The compliant structure absorbs mounting-induced disturbances without transmitting them to the resonator.
Solution Approach 2:
The mounting structure's compliance parameters (flexibility, damping characteristics) are optimized to minimize energy transfer to the resonator at its operating frequency. By carefully selecting and tuning the compliance parameters of the mounting elements, the system achieves both support and isolation functions, reducing measurement errors while maintaining operational stability.
2Measurement precision
If tight manufacturing tolerances are used to achieve high precision measurements, then measurement accuracy improves, but manufacturing costs and device complexity increase
Solution Approach 1:
The sensitive resonator is extracted from direct contact with the rigid mounting structure by introducing compliant isolation elements. This separation removes the resonator from the source of mounting-induced errors, allowing the use of more relaxed manufacturing tolerances for both the resonator and mounting structure while maintaining high measurement precision.
Solution Approach 2:
The mounting structure employs composite construction combining rigid support elements with compliant isolation elements. This composite approach allows the system to achieve both structural integrity and vibration isolation without requiring extreme manufacturing precision in any single component, thereby reducing overall device complexity and manufacturing cost.
3Loss of energy
If the resonator is made more delicate to reduce mounting effects, then energy leakage is minimized, but the resonator becomes more susceptible to breakage and failure
Solution Approach 1:
The compliant mounting structure serves as a protective intermediary that shields the resonator from mechanical stresses and shocks transmitted through the rigid frame. This allows the resonator to be optimized for minimal energy leakage without compromising its mechanical strength, as the compliant structure absorbs and isolates external mechanical disturbances.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides accurate and repeatable measurements of fluid properties by minimizing mounting-induced errors and separating resonant modes, reducing costs and complexity while maintaining precision.
Implementation Method 1
Resonant sensors depend on comparing their resonant characteristics when immersed in a fluid, principally their resonant frequency and damping
Implementation Method 2
employing electromagnetic transducers with soft magnetic materials to reduce interference
Data Source
AI summary
A resonant sensor 1908 is used to determine fluid properties, the resonant sensor 1908 comprising a resonator 108 defining a lengthwise axis and having a central vibrational node (140), and a pair of opposed lengthwise end-portions (125); a support structure including a frame (115) and a set of flexible supports (110) extending from the frame to the central vibrational node and thereby supporting the resonator at the lengthwise midpoint; a driving and sensing assembly, adapted to drive the resonator to resonant motion and to sense resultant motion of the resonator and producing a motion sensed signal, responsive thereto; and a control and signal processing network adapted to control the driving and sensing assembly to drive the lengthwise end-portions in rotation about the lengthwise axis, in opposed rotational directions, and responsive to the motion sensed signal to determine at least one fluid property of a fluid under test in response to the motion sensed signal.